NHS hospitals are contributing to the growing obesity crisis in by selling unhealthy food and drink, an investigation has found.

Research by The Sunday Telegraph discovered that many hospitals up and down the country are offering high-fat and/sugary foods to visitors, staff and patients through fast food chains, coffee shops, pizzerias, patisseries and bakeries.

For example, the investigation found that 92 branches of Costa Coffee, which was recently criticised for selling fruit drinks with four times the recommended daily sugar limits, currently operate in 71 of the 160 NHS trusts in England, including Leeds Teaching Hospitals trust which has 5 branches alone.

The next most common food outlet with 32 sites is WH Smith, which has also come under fire from health campaigners for promoting heavily discounted chocolates, sweets and crisps.

Hospitals guilty of selling junk food include some of the country's most renowned such as Addenbrooke's in Cambridge, which operates a food court with a Burger King, Costa Coffee, Starbucks and pizzeria, and University Hospital Southampton Foundation trust, which also hosts a Burger King and a Costa Coffee shop.

Senior managers at some of the hospitals told The Sunday Telegraph they wanted to close fast food outlets, but were put off by the threat of harsh financial penalties from their subcontractors.

But with latest health figures showing that two-thirds of the British public are either overweight or obese, health and medical experts are urging the NHS to do more to end the sale of junk/sugary food on hospital premises and help combat growing rates of obesity and related conditions such as type 2 diabetes.

Dr Aseem Malhotra, a cardiologist and science director of charity group Action on Sugar, said: "What is going on is really obscene. The NHS needs to get its house in order, because this sends out entirely the wrong message. Hospitals should be a place of healing but instead they are selling sickness."

Simon Stevens, head of NHS England, said the health service needed to take "hard-nosed action" to tackle obesity in the same way that progress had been made against smoking.